Many devices, such as laptop computers and mobile telephones, use light emitting diodes (LEDs) to generate illumination. For example, LEDs are often used to generate backlighting, which illuminates a liquid crystal display (LCD) screen. The amount of backlighting is typically controllable by varying the brightness of the LEDs. Ideally, the operation of the LEDs is optimized so that the LEDs consume as little power as possible while still providing the desired level of illumination.